Alameda County sheriff's Sgt. J.D. Nelson says the unit's front door was unlocked, which may have made officers concerned over safety.

Alameda County sheriff's Sgt. J.D. Nelson says the unit's front door was unlocked, which may have made officers concerned over safety.

Photo: Mike Kepka, The Chronicle

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Announcing details the day after veteran BART police officer Tom Smith was shot and killed by another BART officer, BART police chief Kenton Rainey holds a press conference at BART administration building on Wednesday Jan. 22, 2014 in Oakland, Calif. less

Announcing details the day after veteran BART police officer Tom Smith was shot and killed by another BART officer, BART police chief Kenton Rainey holds a press conference at BART administration building on ... more

Photo: Mike Kepka, The Chronicle

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Announcing details the day after veteran BART police officer Tom Smith was shot and killed by another BART officer, BART police chief Kenton Rainey holds a press conference at BART administration building on Wednesday Jan. 22, 2014 in Oakland, Calif. less

Announcing details the day after veteran BART police officer Tom Smith was shot and killed by another BART officer, BART police chief Kenton Rainey holds a press conference at BART administration building on ... more

Photo: Mike Kepka, The Chronicle

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Police officials stand near the entrance to the Park Sierra Apartments while detectives investigate the fatal shooting of a BART police officer in Dublin, Calif. on Tuesday, Jan. 22, 2014. According to Alameda County Sheriffs spokesman Sgt. J.D. Nelson, one BART police officer accidentally shot and killed another officer while doing a probation check on an individual that lived in the complex. less

Police officials stand near the entrance to the Park Sierra Apartments while detectives investigate the fatal shooting of a BART police officer in Dublin, Calif. on Tuesday, Jan. 22, 2014. According to Alameda ... more

Photo: Paul Chinn, The Chronicle

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Alameda County Sheriffs deputies investigate at the scene of a fatal BART police shooting at the Park Sierra Apartments in Dublin, Calif. on Tuesday, Jan. 22, 2014. According to Alameda County Sheriffs spokesman Sgt. J.D. Nelson, one BART police officer accidentally shot and killed another officer while doing a probation check on an individual that lived in the complex. less

Alameda County Sheriffs deputies investigate at the scene of a fatal BART police shooting at the Park Sierra Apartments in Dublin, Calif. on Tuesday, Jan. 22, 2014. According to Alameda County Sheriffs ... more

Photo: Paul Chinn, The Chronicle

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A BART patrol car is parked near the scene of a fatal BART police shooting at the Park Sierra Apartments in Dublin, Calif. on Tuesday, Jan. 22, 2014. According to Alameda County Sheriffs spokesman Sgt. J.D. Nelson, one BART police officer accidentally shot and killed another officer while doing a probation check on an individual that lived in the complex.

A BART patrol car is parked near the scene of a fatal BART police shooting at the Park Sierra Apartments in Dublin, Calif. on Tuesday, Jan. 22, 2014. According to Alameda County Sheriffs spokesman Sgt. J.D.

Amit Shah reacts after hearing the news that his San Ramon, Calif. neighbor from across the street, BART police officer Tom Smith, was accidentally shot and killed on Tuesday, Jan. 22, 2014. According to Alameda County Sheriffs spokesman Sgt. J.D. Nelson, one BART police officer accidentally shot and killed Smith while doing a probation check on an individual that lived in the complex. less

Amit Shah reacts after hearing the news that his San Ramon, Calif. neighbor from across the street, BART police officer Tom Smith, was accidentally shot and killed on Tuesday, Jan. 22, 2014. According to ... more

Photo: Paul Chinn, The Chronicle

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Law enforcement officers salute as the body of a Bay Area Rapid Transit police officer draped with the American flag is loaded into an Alameda County Sheriff's Coroner vehicle at Eden Medical Center in Castro Valley, Calif., Tuesday, Jan. 21, 2014. The officer was shot while serving a probation search warrant at a residence in Dublin, Calif., according to authorities. less

Law enforcement officers salute as the body of a Bay Area Rapid Transit police officer draped with the American flag is loaded into an Alameda County Sheriff's Coroner vehicle at Eden Medical Center in Castro ... more

Photo: Anda Chu, Associated Press

Image 10 of 14

Alameda County Sheriffs deputies investigate at the scene of a fatal BART police shooting at the Park Sierra Apartments in Dublin, Calif. on Tuesday, Jan. 22, 2014. According to Alameda County Sheriffs spokesman Sgt. J.D. Nelson, one BART police officer accidentally shot and killed another officer while doing a probation check on an individual that lived in the complex. less

Alameda County Sheriffs deputies investigate at the scene of a fatal BART police shooting at the Park Sierra Apartments in Dublin, Calif. on Tuesday, Jan. 22, 2014. According to Alameda County Sheriffs ... more

Photo: Paul Chinn, The Chronicle

Image 11 of 14

An Alameda County Sheriffs deputy stands near the scene of a fatal BART police shooting at the Park Sierra Apartments in Dublin, Calif. on Tuesday, Jan. 22, 2014. According to Alameda County Sheriffs spokesman Sgt. J.D. Nelson, one BART police officer accidentally shot and killed another officer while doing a probation check on an individual that lived in the complex.

An Alameda County Sheriffs deputy stands near the scene of a fatal BART police shooting at the Park Sierra Apartments in Dublin, Calif. on Tuesday, Jan. 22, 2014. According to Alameda County Sheriffs spokesman

Members of the press gather around on Wednesday Jan. 22, 2014 in Oakland, Calif. during a press conference announcing details about the shooting death of veteran BART police officer Tom Smith was shot and killed by another BART officer the day before. less

Members of the press gather around on Wednesday Jan. 22, 2014 in Oakland, Calif. during a press conference announcing details about the shooting death of veteran BART police officer Tom Smith was shot and ... more

Photo: Mike Kepka, The Chronicle

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Announcing details the day after veteran BART police officer Tom Smith was shot and killed by another BART officer, BART police chief Kenton Rainey holds a press conference at BART administration building on Wednesday Jan. 22, 2014 in Oakland, Calif.

Announcing details the day after veteran BART police officer Tom Smith was shot and killed by another BART officer, BART police chief Kenton Rainey holds a press conference at BART administration building on

BART police on Wednesday defended the decision to send in a group of detectives and officers rather than a SWAT team to search a Dublin apartment, an operation that ended tragically when one of the transit agency officers accidentally shot and killed a sergeant who was his supervisor.

Police Chief Kenton Rainey, speaking at a news conference at BART headquarters in Oakland, did not provide details on what happened in the final moments before the shooting of Tom "Tommy" Smith, the 42-year-old head of the detective bureau.

But he said five BART police detectives, two uniformed officers and an Alameda County sheriff's deputy had converged Tuesday to do a probation search on a one-bedroom apartment belonging to 20-year-old John Henry Lee. The robbery suspect was already in custody, having been arrested last Thursday after police say he led San Leandro officers on a chase to Oakland in a car stolen from a BART lot.

The officers conducting the search, Rainey said, were hoping to recover stolen laptops and other property from inside the unit at the Park Sierra Apartments at 6450 Dougherty Road. For some reason that police have yet to explain, a plainclothes detective that sources identified as Officer Michael Maes shot and killed Smith about 1:45 p.m. The only people inside the apartment at the time were officers.

Rainey declined to say whether the detective who fired could have mistaken Smith for a suspect, or if the gun could have accidentally discharged. Officials said the shooting was under investigation by several agencies.

Probation search training

Rainey defended the decision by his officers to conduct the search without a SWAT team, noting that the suspect was behind bars. The chief said BART police officers, like their counterparts in agencies around the state, are qualified to do probation searches.

"Our officers are trained to conduct this type of incident - going out, doing a probation search of an individual who was wanted for committing crimes on BART property," the chief said. "He was in custody. This is not uncommon for law-enforcement officers to do follow-up investigation and try to recover stolen property."

He added, "I'm very confident in the training that our personnel have received to make sure they're prepared to deal with these type of encounters and situations."

The officers went into the apartment through an unlocked front door, said Sgt. J.D. Nelson, a spokesman for the Alameda County Sheriff's Office, which has jurisdiction in Dublin. Noticing that it was unlocked, he said, they may have inferred that the unit was occupied and gone in under a heightened concern for safety.

"They did exactly what was normal," Nelson said.

Longtime BART officers

Daniel Hartwig, who retired from BART last year as a deputy chief, said Smith and Maes were both professional and capable. Smith was a 20-year veteran with experience as a tactical trainer, and Maes came to BART 13 years ago after a stint with Moraga's police force.

"When you go into somebody's house, those are the guys you want to go with," Hartwig said. "What I can tell you is they go in with a plan. This is not something that's developed in five minutes. ... They knew exactly what they were doing. Whatever happened when they went in, it became horrific. And I don't know why."

Officers don't usually split up after making entry into a home, for the sake of one another's safety, said Charles "Sid" Heal, a former Los Angeles County sheriff's commander and the president of the California Association of Tactical Officers.

"It is possible to misidentify," Heal said, "but that's not likely. You usually know where your partner is."

Suspect on probation

The arrest of Lee had been a big deal for BART. Alameda County prosecutors have since charged the young man with robbing a victim at gunpoint of an iPhone, a laptop bag, a Cartier pen and a thumb drive worth more than $1,500 at the Fruitvale Station parking garage in Oakland on Jan. 15.

Lee left the scene in a Honda Accord that had been stolen from the Hayward BART Station, according to an arrest warrant affidavit written by Maes.

Lee was in the Honda early last Thursday when he led police on a chase that ended when he crashed into a tree near Laney College in Oakland, rolled the car and was bitten by a police K-9, Maes wrote. Lee had been given three years' probation in October for a misdemeanor domestic battery conviction stemming from an incident in Hayward, court records show.

Rainey did not say Wednesday whether the shooting was captured on wearable cameras that BART issued to all officers up to the rank of sergeant. Uniformed officers are required to wear the cameras, and they are optional for plainclothes detectives, he said.

The investigation is being handled by the Dublin police force, a division of the Sheriff's Office. All eight officers who were at the apartment have been interviewed, Nelson said.

Maes has been placed on administrative leave. Without identifying the officer, Rainey said he had met with him Tuesday night and reassured him, "We will get through this together as an agency."

His voice faltered as he added, "We're in shock, disbelief, we're numb. We're grieving, and please give us some time."

Common questions about BART police

Like all officers in the state, BART police are afforded full law-enforcement powers, including making car stops and arresting suspects. They can serve warrants anywhere in California.

Are BART officers trained the same way as regular municipal officers?

Yes. They are trained in accordance with the guidelines of the California Commission on Peace Officer Standards and Training, which mandates how all officers in the state must be trained.

Do other major metro transit systems have armed police?

Yes. Across the country, most major-city transit systems have their owned armed police force. In the Bay Area, San Francisco police officers patrol the Muni system and San Mateo County sheriff's deputies patrol Caltrain and SamTrans.

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